Cooler conditions are allowing firefighters some rest ahead of a weather change which is expected to see fire danger increase across Victoria later this week.

The fire danger rating reached extreme in the north of the state last week and severe in other parts, but has dropped back to moderate in most areas.

Firefighters are using the cooler weather to extinguish hotspots and black out active parts of large fires that have already been contained.

The state fire control centre's Peter Appleford says it will provide an opportunity for firefighters to rest before the fire danger increases again on Thursday.

"Certainly towards the end of next week it's going to get quite difficult," he said.

"We are going to have very dry conditions, low humidity, strong winds, high temperatures which really starts to raise those fire danger ratings.

"Depending on how that hot air mass in the middle of Australia behaves, it could be quite a nasty day.

"We'll deal with that when we get to it, but at the moment there's a respite."

Mr Appleford says crews are focusing on a fire at Kentbruck, near Portland in the south-west, which has burnt through 12,000 hectares.

They are also battling a fire at Blampied, in the Daylesford area, that is about 100 hectares in size.

"When we do have these cooler periods [we try to] get all the fires under control and knock them down," he said.

"So that when we do have the more extreme days we are not actually trying to control fires from the day before and look after the new ones, we've got a fairly clean slate and we can get in and jump on the new ones quickly."